Allowable Dimensions for Flush Type Cleanout under API 650

[jeap]

Hi all!

This is a simple question:

A flush type cleanout connection with the next dimensions:

Width: 24"
Height: 36"

can be allowed by API 650? That set of dimensions are not in the tables of the standard.

However, standard 650 in paragraph 3.7.7.1 states that:

'....When a size intermediate to the sizes given in Tables 3-9 through 3-11 is specified by the purchaser, the construction details and reinforcements shall conform to the next larger opening listed in the tables....'

and in the next paragraph:

'3.7.7.2 The opening shall be rectangular, but the upper corners of the opening shall have a radius equal to one-half the greatest height of the clear opening...'

By reviewing the above mentioned tables an figures one can find that width is always larger or equal to height. But it is never mentioned that the opposite is not possible. I do not know if reinforcement calculations for the latter situation are affected and so the tank structure...

I thank you in advance for any help.

Regards,
jeap.

 

[JStephen]

It is not allowable per API-650. I don't have the standard in front of me, but one of the requirements is that the radius has to equal half the height, and you can't do this with an opening taller than it is wide. I think this was in one of the Interpretations, also. You could widen it to 3' or flip the dimensions to 3' wide by 2' high or perhaps just substitute a round manway instead.

That's not to say you can't build the manway, just that it doesn't meet API-650. The API-12D/F type tanks use rectangular manways that are much more poorly designed than the type you are asking about, as do many bolted tanks.

 

[jeap]

Thanks JStephen,

The fact is that the tank, by specification, shall be constructed under API 650. Thus, in order to avoid further observations I'm changing to a 36 x36" connection.

Thanks again.

 

[KiwiTanks]

Carrying on from this theme, our client has specified "a 750mm flush clean-out" (30") for their tank.
From the clause in 5.7.7.1 mentioned above by jeap, we have to use the dimensions as if it were a 900mmx1200mm (36"x48") ("...shall conform to the next larger opening listed..."

In this case, two lots of 450mm raduised corners won't fit in to the 750mm opening....
However, in clause 5.7.7.2 it says to use 1/2 the opening height for the radius (no worries I think this one should over ride the tabled version thru practicality as it's physical impossible to use the tabled version).


However, it also makes the reinforcing plate height from Table 5-11 = 1372mm (54")

Clause 5.7.7.5 goes on to state that "L shall not exceed 1.5h...." --> in this case 1125mm (45") and not 1372mm from the table.
Does this mean that you should install a reinforcing plate to 1372mm, but you can only use 1125mm in the reinforcement calculations? Or does Clause 5.7.7.5 over ride the table version like in the radiused corner problem above, and the reinforcing plate should be only 1125 high?

 

[JStephen]

I'd probably go with the higher repad here. But either way would make about equal sense where the standard isn't clear.